There is a known hybrid vehicle disclosed by Japanese Unexamined Patent Publication No. 2000-332963A which is equipped with a motor connected to an output shaft of an engine where an electric power is supplied to the motor during vehicle acceleration and operates as an electric generator during vehicle deceleration and vehicle braking for performing regenerative braking, and an accumulator is charged with a generated electric power.
However, in case in such a known hybrid vehicle, during a main braking demand when a braking pedal is depressed, almost all of braking forces required are supplied by a regenerative braking based upon prioritizing the regenerative power of a motor, or the motor is operated to generate a regenerative power and at the same time a driving wheel is braked, a braking force of the driving wheel increases extensively. As a result, when a vehicle travels on a slippery road such as a frozen road, the driving wheels slip, to lose vehicle stability during vehicle braking.
An object of the present invention is to provide a braking system for a hybrid vehicle which ensures stability of vehicle braking during vehicle traveling on a slippery road.